How to use Compo

Keep refrigerated or frozen. If it is frozen, defrost before heating.

To heat compo in a microwave.

Dust an old plate with whiting, place a ball of compo on the plate. Heat for about 20 seconds. You should rub whiting on your hands before picking up the hot compo. This should prevent the compo sticking to your hands. Work the compo in on its self until its smooth. You can now press it into moulds. You can reheat left over bits about 3-4 times before it becomes too hard.

To heat compo in a bain-marie.

Place the compo in a plastic bag with some whiting to prevent sticking. Place the bag in the top of the bain-marie, keep the water to just under a boil. The compo should be ready in about 10 min.

Using compo in moulds.

Make sure the compo is smooth, as any folds will show up. With plenty of whiting on your hands firmly press the compo into the mould, paying attention to deep or undercut parts. Depending on the size of the mould you should be able to de-mould the compo between 1-15 mins. If you are pressing out several peaces put the compo decoration in an air tight plastic bag until needed. Trim the compo decoration with a scalpel.

Sticking down the compo decoration.

Runs of compo decoration are best stuck down by heating the back, this heats the glue which is already in the compo. Put a large glazed tile over a pan of boiling water, spray water onto the tile to keep it wet. Rub the back of the compo decoration along the tile until the back starts to melt. Place the compo decoration where you need it. For long pieces you may need to use some slim nails as well. Wood glue is good for awkward pieces.

Drying times.

You have about an hour after the compo has come out of the mould while it is still pliable after that it starts to dry out. After 24 hours it’s hard and gesso etc can be applied. But it will keep drying over weeks, you may find small cracks appear. This happens to all compo it’s partly the compo drying out and partly the wooden frame underneath.

Modelling compo.

Hot compo can be modelled with a hot wet tool or fingers. When hard it can also be carved. Compo is good for backing decoration. For example a cartouche on the top of a mirror is fixed to a metal bar coming out of the wooden frame. Hot wet compo is places over the bar and smoothed into the back. Keep your hands wet with hot water and use compo from a bain-marie if you are backing a large area.

Finishing off.

After the new compo decoration is dry fill in any gaps with hot wet compo on a moulding tool or use milliput.